Among various color recording methods, a recording method using an inkjet printer as a typical method performs recording by generating small droplets of ink and attaching the droplets to a recording material such as paper. The advance of inkjet technology has also increased use of the inkjet recording method in the field of high-resolution printing, which previously had been achieved by silver halide photography or offset printing. In recent years, there has been a further growing demand for this method for industrial purposes, and high-speed printing performance has also been desired.
Recording media having an ink-absorbing layer, such as inkjet exclusive paper and gloss paper for inkjet, as well as recording media having low ability to absorb ink; i.e., having no ink-absorbing layer, such as general-purpose plain paper, are used in inkjet recording methods using aqueous ink. Since the latter recording media are less permeable to ink, printed matter has weak rubfastness. Particularly, a phenomenon called mottling may occur when an aqueous pigment ink is used.
Mottling refers to the phenomenon in which, for example, when an image with a large amount of ink attached, such as a solid image, is recorded, the amount of ink attached exceeds the capacity of a recording material to absorb ink, whereby the ink fails to be uniformly absorbed to the recording material so that droplets of unabsorbed ink are maldistributed and fixed on the recording material, causing irregular image unevenness.
In response to the problems described above, Patent Documents 1 and 2 disclose ink that reportedly yields an image having good rubfastness and high quality by controlling the permeability of paper by means of a surfactant and a penetrant. Also, Patent Document 3 discloses a coating material comprising a compound represented by the formula (1) described later as a coalescing agent.